Install “wimtools” so we can use wimsplit as the .wim file is usually too big for FAT32

Extract .iso

7z x Win10_21H1_English_x64.iso -owin10

Split install.wim (in 3GB parts, as it is enough to just get two parts )

cd win10/sources
win10/sources$ wimsplit install.wim install.swm 3000
Writing "install.swm" (part 1 of 2): 0 MiB of 4654 MiB (0%) written
Writing "install2.swm" (part 2 of 2): 2737 MiB of 4654 MiB (58%) written
Finished writing split WIM part 2 of 2

Remove install.wim

rm install.wim

Create partition table and filesystem

parted -s /dev/sde -- mklabel msdos
parted -s /dev/sde -- mkpart primary fat32 1M -1s
parted -s /dev/sde -- toggle 1 boot
mkfs.fat -n WIN10_EN /dev/sde1

Mount USB stick and copy files

mount /dev/sde1 /mnt
cd ..
cp --preserve=mode,timestamps -Rv * /mnt/
umount /mnt